Lately, the study of peroxides multifunctional initiators has been explored in the scientific and industrial field. These initiators are able to increase the reaction rate in a free radical polymerization without decrease the molecular weight of the formed polymer. Besides that they can also generate branches in the polymeric chain, changing the polymer structure. Copyright © 2009, AIDIC Servizi S.r.l.17 18011806Machado P.F.M.P.B.Lona, L.M.F.,2005, Development of a Software to Simulate Free Radical Polymerization of Linear and Branched Polymers using Mono-and Bi-Functional Initiators, E. Symp. on Comp. Aided Proc. Eng.-15, 2005, 20 A, 445-450Scorah, M.J., (2005) Modelling of Free Radical Polymerization of Styrene and Methyl Methacrylate by a Tetrafunctional Initiator, , PhD thesis, Dept. of Chem. Eng, University of Waterloo, Waterloo, Ontario, CanadaScorah, M. J.Dhib, R.Penlidis, A., 2007, Recent Advances in the Study of Multifunctional Initiators in Free Radical Polymerizations, Macrom. React. Eng., 1, 209-221